Plan for the session Guest lecture by Eric Feron(1 hour) Quiz on design of Dynamic Systems(15 minutes) Review of reliability Improvement Case Study --Router Bit Life 35 minutes) mit 人 16881
Plan for the Session • Guest lecture by Eric Feron (1 hour) • Quiz on Design of Dynamic Systems (15 minutes) • Review of Reliability Improvement Case Study -- Router Bit Life (35 minutes) 16.881 MIT
Learning objectives Introduce some basics of reliability engineering Relate reliability to robust design Practice some advanced construction techniques for orthogonal arrays Introduce analysis of ordered categorical data Practice interpreting data from robust design case studies mit 人 16881
Learning Objectives • Introduce some basics of reliability engineering • Relate reliability to robust design • Practice some advanced construction techniques for orthogonal arrays • Introduce analysis of ordered categorical data • Practice interpreting data from robust design case studies 16.881 MIT
Reliability terminology Reliability function R(t)-- The probability that a product will continue to meet its specifications over a time interval Mean Time to Failure MTTF-- The average time t before a unit fails MTTF=R(t)dt Instantaneous failure rate nt) n(t=Pr(System survives to t+dt(System survives to t A(5)d5 R(t)=e mit 人 16881
Reliability Terminology • Reliability function R ( t) -- The probability that a product will continue to meet its specifications over a time interval • Mean Time to Failure MTTF -- The average ∞ time T before a unit fails MTTF = ∫ R ( t )dt • Instantaneous failure rate λ( t ) 0 λ( t) = Pr(System survives to t + dt System survives to t) t R ( t) = e − ∫0 λ(ξ )dξ 16.881 MIT
Typical Behavior Early failure period often removed by burn-in Wear out period sometimes avoided by retirement What will the reliability curve R(t look like if early failure and wear out are avoided? Earl Wear n(tailure Useful life out mit 人 16881
Typical Behavior • Early failure period often removed by “burn-in” • Wear out period sometimes avoided by retirement • What will the reliability curve R ( t) look like if early failure and wear out are avoided? Early Wear λ( t) failure out Useful life 16.881 t MIT
Weibull distributions Common in component failure probabilities (e.g, ultimate strength of a test specimen Limit of the minimum of a set of ndependent random variables R(t) R(t)= e( n s=l mit 人 16881
Weibull Distributions • Common in component failure probabilities (e.g., ultimate strength of a test specimen) • Limit of the minimum of a set of independent random variables s − t−to R(t) = e η 16.881 MIT